Dozens of chemicals that are commonly found in human drugs and cosmetic products are showing up in an unexpected place: the brains of fish in the Puget Sound.
A study by NOAA Fisheries’ Northwest Fisheries Science Center and the University of Washington tested the waters for 150 different contaminants. They found 81 of them in wastewater flowing to Puget Sound estuaries.
Researchers tested three things: effluent from wastewater treatment plants, water from Puget Sound estuaries, and the fish themselves. Although they expected to find higher levels of chemicals in the estuaries nearest the treatment plants, they also found unexpectedly high levels in waters farther from the plants that were included as reference sites.Pre-conference workshops Repairing Entrenched, Incised, and Degraded (Urbanized) Streams – Techniques and Case Studies Monday August 28, 2017 and BMP Selection to Improve Your Watershed Monday August 28, 2017. You may register for these without also registering for the annual conference. Download the StormCon Conference Program here.
The chemicals in question range from antibacterial compounds to substances found in prescription drugs. Two found in large quantities were metaformin, a drug used to treat diabetes, and fluoxetine, an antidepressant marketed as Prozac. Although many of the compounds detected are not toxic to humans, they are present in concentrations that can affect the behavior, growth, and reproduction of fish like Chinook salmon and Pacific staghorn sculpin. The fact that the substances are found in combination raises further questions about how they might interact and affect fish and other aquatic organisms. Researchers estimate as much as 300 pounds per day of the contaminants might be entering the waters of Puget Sound via treatment plant effluent.
An unrelated study reported three years ago in Scientific American showed that fish exposed to certain human antianxiety drugs such as Valium and Xanax display more aggressive behavior and consume food faster. The fish were more likely to swim into unfamiliar waters, thus putting themselves at risk from predators, and their increased rate of consumption of zooplankton—which in turn consumes algae—potentially lead to an increase in algae blooms.
We can’t necessarily affect what’s coming out of the wastewater treatment plants, but stormwater professionals are very much concerned with keeping surface waters “fishable and swimmable.” The drugs, which are not removed by standard treatment, enter the water in two ways. Some are excreted in urine, but the larger and more damaging source is people flushing their unused drugs down the toilet. More—and more widely publicized—programs to encourage people to return their unused drugs to pharmacies for proper disposal would help alleviate that problem. Eventually, new treatment methods—ozone, for one—might make wastewater treatment plants better able to remove the drugs as well.
Although the NOAA study did not specifically address the potential effects on humans of eating fish with high levels of these substances, it’s a question worth investigating. However, one scientist quoted in the Scientific American article notes that the chances of a person getting a significant amount of Valium from eating contaminated fish is small: “You’d have to eat four tons of perch from the river to get one tablet of the drug.”Add Stormwater Weekly and Water Efficiency Weekly to your Newsletter Preferences and keep up with the latest articles on water: green infrastructure, smart meters, stormwater drainage and management, water quality monitoring and water treatment.